This is an application to continue research originally started in 2001, and expanded into a longitudinal study, known as the Virginia Cognitive Aging Project (VCAP), in 2005. Over 2,300 adults 18 - 95 years old have now completed at least two longitudinal occasions, with an average of 2.7 occasions and an average time in study of 5.1 years. The research proposed in the next funding period will extend the investigation of short-term longitudinal change in a broad variety of cognitive measures, with particular emphasis on adults under the age of 80. Although previous studies have found little or no cognitive change in longitudinal comparisons involving young and middle-aged adults, this research employs three methodological innovations, variable retest intervals, measurement bursts at each occasion, and continuous recruitment of new participants, that help distinguish age effects from experience (retest) effects, and that increase sensitivity to detect change by taking into account normal short-term variability in performance. Among the primary questions to be investigated are when does normal age-related cognitive change begin, the degree to which changes in different cognitive variables are independent of one another at different periods in adulthood, the role of prior test experience on the direction and magnitude of cognitive change at different ages, the degree to which factors such as one's cognitive or physical lifestyle moderate the amount of age-related change in different cognitive abilities at various periods in adulthood, and how early can normal and pathological trajectories of cognitive aging be distinguished. Specific aims during the next grant period are to: (1) Expand the characterization of normal cognitive aging across the range from about 18 to 80 years old; (2) Extend the investigation of the role of experience effects on cognitive change; (3) Investigate the structure and nature of cognitive change across different levels of analysis and across a wide range of ages; and (4) Increase sensitivity of VCAP tests to detect early stages of cognitive pathology among VCAP participants.